“We plead that you intervene on this issue and ask the officials in Mendoza who have the polar bear Arturo prisoner to accept Arturo's transfer to the reserve so he can live in suitable conditions,” reads a petition on the Change.org website, which has more than 600,000 signatures. A similar petition from Greenpeace has gathered more than 200,000 signatures so far.

Polar bear experts say Arturo, who's been dubbed "the world's saddest polar bear," can be regularly seen pacing in his enclosure, baring his teeth, tilting his head and rocking back and forth, all considered signs of stress in polar bears.

The petitioners point out that Arturo’s last companion died in 2012 and say Argentina’s warm temperatures and the zoo’s comparatively small enclosure are diminishing the bear’s quality of life.

For example, Arturo has access to a shallow pool of water that is about 20 inches deep, while in Canada he would have access to a large, chilled pool more than 60 feet deep. In addition, he would be allowed to socialize with a number of other polar bears that currently live at the zoo.

But the director of Argentina’s zoo in Mendoza says that sedating the bear for the nearly 6,000-mile journey would likely kill him.

“Arturo is close to his caretakers. We just want everyone to stop bothering the bear,” zoo director Gustavo Pronotto said in an interview. “We must avoid a big mistake, like his death during the trip or upon arrival. One must evaluate the risks carefully. He is old, and this would require many hours of anesthesia.’

Arturo is 28 years old; polar bears typically only live about 15 years in the wild. And while they can live beyond 30 years in captivity, it’s clear that Arturo is in the last few years of his life.

Still, that hasn’t stopped prominent figures, including former U.S. House Speaker Newt Gingrich, from speaking out on the issue.

“If you love animals the way I do, please sign the petition to help the Argentinian polar bear, Arturo," Gingrich wrote on his Facebook page. "His current living situation is very sad, and he deserves to be saved."